Chair back



FIG. 1 is a front perspective view of a chair back showing the new design;

FIG. 2 is a slightly reduced front view of the chair back of FIG. 1;

FIG. 3 is a slightly reduced rear view of the chair back of FIG. 1;

FIG. 4 is a slightly reduced left side view of the chair back of FIG. 1;

FIG. 5 is a slightly reduced right side view of the chair back of FIG. 1;

FIG. 6 is a slightly reduced top plan view of the chair back of FIG. 1; and,

FIG. 7 is a slightly reduced bottom plan view of the chair back of FIG. 1.

The broken lines shown are for environmental illustrative purposes only; and form no part of the claimed design, the claimed design is for a product confirugation only. 

We claim the ornamental design for a chair back, as shown and described. 